Carbohydrate Cravings, Serotonin and Satiety

Introduction by: Jessica Apple

Diabetes and depression often go hand-in-hand, and recently I spoke to my doctor about my own case of the blues.  “Your diet may have something to do with it,” he said.

“What?” I asked.  I had no idea what he was talking about.  I eat a very low-carb diet, which helps me keep my blood sugar levels in the normal range almost all of the time.  And there is nothing depressing about normal blood sugar levels.  ”I don’t understand what you  mean,” I said to my doctor.

“The Atkins diet is associated with depression,” he said.  “Maybe you should eat more carbohydrate and cover it with insulin.”

I’m not on the Atkins diet, but I do limit my carbohydrate intake to 30-50 grams a day, depending on how much I exercise.  And since I can’t stand the idea of out-of-control blood sugar levels, I blew off my doctor’s suggestion about increasing my carbohydrate intake.  I was, however, curious about the link between a low-carb diet and depression and when I began to look into it, I came across the work of Judith Wurtman, co-author with Nina Marquis, M.D , of The Serotonin Power Diet.  Judith’s research has focused on the relationship between a person’s emotional state, carbohydrate craving and brain serotonin. With her husband, Richard, she demonstrated that overeating is often related to the need to decrease stress. They showed that when carbohydrate-rich foods are eaten, the resulting  production of brain serotonin improved emotional stability.

To find out more, I contacted Judith and asked her about her work.  And what, I asked specifically, can someone who has diabetes (and can’t consume a lot of carbohydrates) do?  Here is an essay she wrote for ASweetLife.


Carbohydrate Cravings, Serotonin and Satiety

By: Judith Wurtman

In the 1970s John Blundell and researchers at the University of Leeds discovered that satisfaction or satiety after eating comes not from filling or stuffing the stomach but from making a chemical in the brain called serotonin.[1] And when serotonin is not made, the eater feels a vague dissatisfaction with the meal just consumed. Fullness is present but not satiety.

Blundell’s research found that if lab animals were treated with a drug that increased serotonin activity, rats would stop eating sooner  than their untreated cage mates  even if there was still food in their food bowls.  The researchers dubbed serotonin the satiety chemical or neurotransmitter  and  confirmed its role in halting food intake. It can turn off eating as completely as drinking water turns off thirst. When serotonin is active, all interest in eating vanishes.

Judith Wurtman

Serotonin is unlike other neurotransmitters in the brain because its synthesis depends on whether or not carbohydrates are eaten.  If you choose to eat or not eat a potato or rice, you will be affecting the fate of this chemical.  Avoid carbohydrates and no serotonin is made; eat them and the synthesis begins immediately.

There is nothing in a potato or pasta per se  that goes into the manufacture of  serotonin.  However when any non-fructose carbohydrate is digested, the  resulting release of  insulin allows an amino acid, tryptophan, to enter the brain.  Serotonin is made from tryptophan and dependent on insulin to get it into the brain.

Eating protein prevents tryptophan from entering the brain because the digestion of protein causes the  blood to  fill up with other amino acids that prevent  tryptophan from entering the brain.

The dependence of serotonin synthesis on carbohydrate consumption and insulin poses a problem for diabetics. Carbohydrate has to be eaten alone or with very little protein for serotonin to be made. Meals that contain more protein than carbohydrate will prevent this and leave the diabetic eater feeling vaguely dissatisfied. The stomach may be full but that comfortable feeling that comes from being satiated may be missing.

Not being able to make serotonin because of the limitations of carbohydrate consumption can also have an effect on mood. This was a discovery that I made and published along with my husband and in subsequent studies with Harris Lieberman, Ph.D and Bonnie Spring, Ph.D.  We discovered that many people experience a deterioration in their moods late in the afternoon along with a craving for something starchy or sweet.  We studied their moods after  eating carbohydrate and found that small amounts (about 30 grams) improved their moods, increased their concentration and made them feel more energetic.

Craving for carbohydrates in association with a deteriorating mood is not limited to afternoon carbohydrate cravers, however. Women with premenstrual syndrome (PMS) , people experiencing the winter blues or Seasonal Affective Disorder and even ex-smokers  find themselves eating carbohydrates when experiencing  depression, anxiety, anger, exhaustion and the inability to be attentive or focus . Eating carbohydrate seemed to relieve these moods presumably by increasing serotonin.  Avoiding carbohydrate may make it harder to endure the changes in mood of PMS, for example, or put people into a permanent grumpy state. When the Atkins diet was popular, people were said to develop an Atkins attitude that was somewhat similar to PMS.

Recently I’ve discovered that increasing serotonin by eating carbohydrates at specific times of the day is effective in helping people lose weight.  The ‘spoil the appetite’ effect of a small amount of carbohydrate before the meal makes it easier for the dieter to be satisfied with diet size portions.  People whose weight gain was caused by antidepressants or mood stabilizers have an even greater problem losing weight because somehow their medications are increasing their appetites and taking away the feeling of contentment after they eat.   At a weight loss clinic I developed and ran at a Harvard psychiatric hospital, we developed a food plan that included a carbohydrate snack prior to lunch and again in the late afternoon. The increase in serotonin seemed to turn off the cravings and need to eat generated by the medications.

It should be possible to develop a food plan for diabetics that permits carbohydrates to be eaten and serotonin to be made. Low glycemic carbohydrates such as lentils, beans, whole grains,  and high fiber foods may be the optimal source of carbohydrates. Even though some of these foods such as beans contain protein, the amount is too small to interfere with the ability of tryptophan to get into the brain.  We did have a few type 2 diabetics among our weight loss  clients and worked with an MIT research dietician to develop a food plan that was compatible with their needs.

Eating enough carbohydrate to produce serotonin during the dark days of winter will make the wait until spring more bearable . Having a carbohydrate snack during the afternoon doldrums will increase your ability to tolerate a difficult workload or difficult teenagers. And if faced with a meal of vegetables and chicken slivers, eating a roll or whole grain crackers or cup of bean soup before starting the main course will make you actually feel satisfied when the last piece of lettuce is eaten.


[1] Wurtman, J and Wurtman R  Life Sciences, Vol 24, 845-904, l979  Wurtman J, Moses P and Wurtman R, J Nutr 113: 70-78 l983.

For further reading:

Fernstrom J Wurtman R, Brain serotonin content: physiological dependence on Plasma tryptophan levels, Science 1971 173:149-52,
Fernstrom J and Wurtman R, Hammarstrom-Wiklund,J Rand, W, Munro H, Davidson C Diurnal variations in plasma concentrations of tryptophan , tyrosine and other neutral amino acids: effect of dietary protein intake. Am J Clin Nutr l979, 32: 1912-22
Schaechter J Wurtman R, Trptophan availability modulates serotonin release from rat hypothalamic slices J Neurochem l989 53: 1925-33ntervention using d fenfluramine Health Psychol 1991: 10:216-23
Wurtman R and Wurtman J Carbohydrates and depression Sci Am l989 68-75
Find the Serotonin Power Diet on Facebook or at serotoninpowerdiet.com

Comments (13)

  1. Jeff N. at

    Thanks for this, Jessica — it fits with own experience, but I hadn’t heard of this research.  I really appreciate all the information here at “A Sweet Life,” the great writing, and the courage and wholeheartedess of all the contributors.

  2. Jeff N. at

    Judith, thanks to you, too, for your research and bringing it to us here.

  3. Jessica Apple
    Jessica at

    Jeff, thanks so much for the wonderful feedback!
     

  4. Jennifer at

    This is very interesting. It sounds right. But I wonder if any of the research has looked at whether this phenomenon holds up in the long term, i.e., whether the carb-serotonin connection persists when someone has been eating few to no carbs for many months or years.

  5. Cleo at

    It would be nice to see a list of carbohydrate snack (appetite diminishing) suggestions.  I agree that avoiding carbohydrates to control BS is ultimately untenable, but eating small doses of carbs sometimes triggers eating too many carbs (for some of us), so relearning to eat carbs can seem daunting, like an alcoholic trying to drink a little bit.  Any known serotonin creating snacks that are less likely to induce overeating?

  6. diabetes at

    Here is an interesting finding…which causes which?

    Studies show that anti depressants cause diabetes but the diabetic is often depressed

    In Fact those who take anti depressants better have their blood sugar checked regularly because they can trigger diabetes

    Atkins is NOT good. The fact that millions of people believe carbs are bad is a media crime from this man diet.

    With  low carbs comes lack of concentration,depression and an unhealthy diet. Healthy people know that Carbs are the backbone of all healthy diets.

    We have lost our way and are so uneducated on how to eat…sad

  7. Dear Cleo, I would think that the best snacks are those with a relatively low glycemic index. Perhaps high fiber breakfast cereal, multigrain bread, even something that is corn based as corn is high in fiber. The best thing to do is to check with a dietician. Rice would be a good snack and if you like sushi, then you could eat sushi with vegetables in the middle like a California roll. Some other cultures take sticky rice and make rice balls with some dried fruit inside for a little flavor. If popcorn is high enough in fiber that might make a good snack.

  8. Dear Jennifer, Serotonin needs to be made  all the time but animal studies including one we did show that if not enough tryptophan gets into the brain, there may be a decrease in serotonin. On the other hand it can be reversed IF insulin is available to drive the process. So avoiding carbs for months and years is not a good thing but fortunately people will not be in a permanent bad mood, I hope, if they do so. However Atkins folks may really be suffering from lack of serotonin.
    By the way you should know that women go through life with less serotonin than men so when our levels drop we may be more vulnerable than men to mood problems.  

  9. Jennifer Linsdale at

    I think this is why they call them “comfort foods.” They make us feel better – secure, etc. I mean, who doesn’t like a rich & creamy chocolate eclair – it literally lights you up with serotonin!
    If we want to win the battle over weight gain, we have to replace that food-induced serotonin with something that comes with fewer calories!
     
    Jen
    http://www.bestlowcarbdesserts.com
     

  10. All of this, the need to eat when stressed, tired or PMSing, is very much my own experience.  It makes very good sense to me and it’s something I struggle with now as a stay-at-home mother to three.  A stressful day with the kids can drive me straight toward the cookie jar.  I’ve never had weight issues, but now that I am a diabetic, I need to keep it in check. 
    This is great research, Judith and very informative for those of us who have to watch our carbs and then wonder about feeling somewhat depressed.  I have never struggled with depression, but I’ve found myself a few times recently wondering why I can’t shake the blues.
    Thank you for bringing this to us, Jessica.

  11. Croanar the Defiant at

    WOW…. this explains a LOT. Thanks for this info!

  12. Jared at

    Great information!  Thanks for sharing your research and writing.  I have a question.  My issue with carbs, blood sugar, and mood is that I’m hypoglycemic and not diabetic.  So, if I don’t eat every 3 or 4 hours at the most I get moody.  It’s been a real challenge.  I did P90X a couple years ago and got pretty lean, but my mood was pretty consistently crap.  My question is this.  If a person does a  low carb diet, are there natural supplements (NOT DRUGS) that he/she can take to manipulate the body to produce more serotonin?  I’d love the benefits of going low carb with being the type of man my wife can live with.  Any ideas or suggestions would be hugely appreciated.

  13. Marti J. at

    Interesting discussion… I may be an outlier, but in the last 4 years of eating low carb I’ve found that my mood gets better, the fewer carbs I eat. Nearly every time I eat too many carbs I get unstable, and my best days are when I don’t eat many carbs. Is there room in your theory for personal variability, or do you think we’re all measuring carbs and defining “low carb” in different ways?

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